1. Field of the Invention
The present invention relates to a digital audio signal transmission apparatus, more particularly, to a process for multiple-channel audio signals for use with an apparatus for recording and reproducing digital audio signals.
Audio apparatuses with surround reproducing systems that provide sound effects have been disclosed and sold. The surround reproducing systems with four speakers (for example, two-front-and-two-rear-speaker system and three-front-and-one-rear-speaker system) are known. In the field of movies, this tendency is much drastic. Analog surround systems are being replaced with digital surround systems. Six-channel surround systems and eight-channel surround systems have been proposed.
U.S. Pat. No. 5,349,384 and EP laid-open publication Nos. 0600467, 0600493 by the same applicant as related arts (U.S. patent applications having the respective Ser. Nos. 08/159,238 now 08/480,934 and 08/159,455, corresponding to the above two publications are pending).
When a movie video tape is sold as a video soft tape, the surround signals recorded on the tape may be partially changed or may be not changed. However, most users have only two-channel stereo reproducing systems using two speakers. Thus, although the video soft tape records the surround signals, most users cannot fully reproduce them. In addition, when only left and right components of sound signals are output, important audio information such as speech portion may be lost.
When a reproducing apparatus such as a digital VCR reproduces audio signals on a plurality of channels from a video soft tape, the audio signals of the plurality of channels should be composited as conventional L and R components and then the resultant signals should be output. Thus, the hardware for processing audio signals of the digital VCR becomes complicated.
When manufacturers of video soft tapes convert surround signals into two-channel stereo signals, the hardware of the VCR does not increase. However, the value of the of the video soft tapes is deteriorated. Thus, this method is not preferable for the manufacturers of the video soft tapes.